1. Field of the Invention
This invention relates to a device which corrects a focused image tremble of an optical device due to hand tremble and so on.
2. Description of the Related Art
Conventionally, there are some optical devices, for example a camera, which are provided with a focused image tremble correcting device for correcting a focused image tremble due to a hand tremble and so on. Japanese patent gazette No. 2641172 suggests a correcting device which corrects a focused image tremble by moving a correcting optical system in two directions which cross at right angles and are perpendicular to the optical axis of the correcting optical device. The two directions are the pitch direction and the yaw direction.
In the correcting device, a fixed frame which holds the correcting optical system is provided with driving mechanisms and leading mechanisms with respect to each of the pitch and yaw directions. Each of the driving mechanisms includes an electromagnetic coil, and each of the leading mechanisms includes a combination of a shaft and a coil spring. Two driving mechanisms and two leading mechanisms are provided for moving the fixed frame in the pitch direction, and two other driving mechanisms and two other leading mechanisms are provided for moving the fixed frame in the yaw direction. Namely, the fixed frame is moved in the pitch direction by a pair of the driving mechanisms and a pair of the leading mechanisms, and is moved in the yaw direction by another pair of the driving mechanisms and another pair of the leading mechanisms.
Accordingly, in order to precisely drive the fixed frame in a direction parallel to the pitch direction, members included in the leading mechanisms need to be precisely assembled, and further high precision of the positional relationship between the pair of leading mechanisms is required. Also, in order to precisely drive the fixed frame in a direction parallel to the yaw direction, the same levels of precision are required.
Namely, in each of the leading mechanisms, it is necessary to improve the precision of engagement of the shaft and the coil spring, and further the shafts of each of the pair of the leading mechanisms should be placed so as to be parallel to the leading direction of the leading mechanisms.
Accordingly, it is not easy to assemble and place the leading mechanisms, so it is difficult to precisely drive the fixed frame in the pitch and yaw directions. Further, if the assembly and placement of the leading mechanisms are not accurately carried out, when the fixed frame is driven, a large load is added to each member of the leading mechanisms, so the durability of each member becomes low.
Therefore, an object of the present invention is to provide a focused image tremble correcting device, the structure of which is simple, and which is able to perform correction with high precision.
In accordance with an aspect of the present invention, there is provided a focused image tremble correcting device comprising: a tremble detector that detects a focused image tremble of an optical device; a correcting optical system for correcting the focused image tremble, the correcting optical system being included in an imaging optical system of the optical device; a first driving unit; a second driving unit; and a controller that controls the first and second driving units to move the correcting optical system such that the image tremble can be cancelled.
The first driving unit includes: a first rotating board which is held being rotatable around a first axis parallel to the optical axis of the correcting optical system; and a first driving mechanism that drives the first rotating board. The first rotating board has a first opening. The second driving unit includes: a second rotating board which is held being rotatable around a second axis which is parallel to the optical axis; and a second driving mechanism that drives the second rotating board. The second rotating board has a second opening. The correcting optical axis is supported by a first pair of inner sides of the first opening and a second pair of inner sides of the second opening. The first pair of inner sides is parallel to a first straight line that is perpendicular to the optical axis and the first axis. The second pair of inner sides is parallel to a second straight line perpendicular to the optical axis and the second axis.
Preferably, when the correcting optical system is driven in accordance with a rotation of the first rotating board, the correcting optical system is moved along the first pair of inner sides, being led by the second pair of inner sides, and when the correcting optical system is driven in accordance with a rotation of the second rotating board, the correcting optical system is moved along the second pair of inner sides, being led by the first pair of inner sides.
Preferably, in a two-dimensional coordinate system on a plane which is perpendicular to the optical axis of the correcting optical system that is positioned at a standard position in which the optical axis of the correction optical system is coaxial with an optical axis of other optical systems included in the imaging optical system, an origin of the two-dimensional coordinate being an intersection point of the optical axis of the correction optical system and the perpendicular plane, an X-axis of the two-dimensional coordinate being a straight line connecting the origin and an intersection point of the first axis and the perpendicular plane, a Y-axis of the two-dimensional coordinate being a straight line connecting the origin and an intersection point of the second axis and the perpendicular plane, a rotational angle xcex81 of the first rotating board which is rotated to cancel the focused image tremble and a rotational angle xcex82 of the second rotating board which is rotated to cancel the focused image tremble are calculated based on the formulas to follow.
xcex81=tanxe2x88x921(p2/(d1+p1))xe2x80x83xe2x80x83(1) 
xcex82=tanxe2x88x921(p1/(d2+p2))xe2x80x83xe2x80x83(2) 
(herein, d1: an absolute value of an X coordinate of the first axis in the two-dimensional coordinate
d2: an absolute value of a Y coordinate of the second axis in the two-dimensional coordinate
p1: an absolute value of an X coordinate of the optical axis of the correcting optical system being at an aimed position at which the correction optical system has to be moved to cancel the image tremble,
p2: an absolute value of a Y coordinate of the optical axis of the correcting optical system being at the aimed position)